1. Field of the Invention
This invention relates to electric motors and in particular to electric motor structures for use in vacuum cleaners and the like.
2. Description of the Background Art
In one known form of electric motor, the field windings are wound on spaced C-shaped poles. The legs of the opposed C-shaped poles may be spaced apart to define an air gap. Current flow through the coil wound on the bight portion of the C-shaped pole produces flux in the salient pole legs. Because of the reluctance, armature reaction is reduced, thus providing improved performance of the motor.
A motor utilizing split poles is illustrated in U.S. Pat. No. 1,622,204 of Herman Papst.
In U.S. Pat. No. 2,000,699 of William R. Harding, an arc welding generator is disclosed utilizing spacers of non-magnetic material between an upper portion and a lower portion of the main frame of the motor.
In U.S. Pat. No. 2,073,526, Giuseppe Massimo Pestarini discloses a dynamo-electric machine wherein the stator frame is provided with a layer of suitable magnetically insulating or less permeable material at suitable points in place of air gaps. Pestarini further teaches that in lieu of the inserted material, the section of the stator frame at these points may be reduced, to cause saturation at a relatively small value of flux.
Doran D. Hershberger discloses, in U.S. Pat. No. 3,421,034, the use of an elongated slot extending across the yoke section. After the core is cut to define the slots, bonding material in an unhardened state is applied.
Charles A. Thomas discloses, in U.S. Pat. No. 2,465,824, a dynamo-electric machine wherein the stator segments are separated by nonmagnetic spacers and secured together mechanically by conventional nonmagnetic curing means.